The long-term goals of this project are: (1) to gain an increased understanding of how electrical noise affects the detectability and discriminability of mechanical cutaneous stimuli, and (2) to establish a scientific foundation for the development of a noise- based technique for improving tactile sensation in humans. Under certain conditions, the presence of noise can increase the detectability of a stimulus. Little is known about this phenomenon, however, primarily because it has been investigated using narrow experimental designs. Accordingly, in this project, we propose to study how various forms of electrical noise alter the detectability and discriminability of subthreshold and suprathreshold mechanical cutaneous stimuli. We will examine these issues in psychophysical experiments on healthy human subjects. In the experiments, local indentations and electrical noise signals will be applied to each subject's right middle digit using a cylindrical probe. With this system, it is possible to apply a single (common) electrical noise signal or multiple independent electrical noise signals. The specific aims for this project are: (1) to test the hypothesis that electrical input noise can enhance (degrade) the detection of subthreshold (suprathreshold) mechanical stimuli, (2) to test the hypothesis that independent electrical noise sources can enhance (reduce) noise-mediated improvements (decrements) in the detection of subthreshold (suprathreshold) mechanical stimuli, (3) to test the hypothesis that electrical input noise can enhance (degrade) the discrimination of qualitatively different subthreshold (suprathreshold) mechanical stimuli, and (4) to test the hypothesis that independent electrical noise sources can enhance (reduce) noise-mediated improvements (decrements) in the discrimination of qualitatively different subthreshold (suprathreshold) mechanical stimuli. This project could eventually lead to the development of a noise- based technique that could be used to improve tactile sensation in humans. Such a technique could be used to restore sensory function in individuals with elevated sensory thresholds, such as older adults and patients with peripheral neuropathies.